FDA approves Elaprase (idursulfase) for Hunter syndrome

The U.S. Food and Drug Administration (FDA) has approved Elaprase (idursulfase), the first product for the treatment of Hunter syndrome (Mucopolysaccharidosis II, or MPS II), a rare inherited disease which can lead to premature death. Elaprase is a new molecular entity, which is an active ingredient never before marketed in the United States.

Hunter Syndrome, which usually becomes apparent in children one to three years of age, is a disease in which the person's body is defective in producing the chemical iduronate-2-sulfatase, which is needed to adequately breakdown complex sugars produced in the body. Symptoms include growth delay, joint stiffness, and coarsening of facial features. In severe cases, patients experience respiratory and cardiac problems, enlargement of the liver and spleen, neurological deficits, and death.

Elaprase was designated as an orphan product by FDA. Orphan products, such as Elaprase, are generally developed to treat rare diseases or conditions that affect fewer than 200,000 people in the U.S. The Orphan Drug Act provides a seven-year period of exclusive marketing to the first sponsor who obtains marketing approval for a designated orphan product. Hunter syndrome is diagnosed in approximately one out of 65,000 to 132,000 births.

"This is the first product that brings help to a very small group of seriously ill patients who have no other treatment option," said Dr. Steven Galson, Director, Center for Drug Evaluation and Research. "This approval is a good example of how the Orphan products program can benefit the public health with urgently needed products that would otherwise not be commercially available."

Elaprase was approved after a randomized, double-blind, placebo-controlled study of 96 patients with Hunter syndrome showed that the treated participants had an improved capacity to walk. At the end of the 53–week trial, patients who received Elaprase infusions experienced on average a 38-yard greater increase in the distance walked in six minutes compared to the patients on placebo.

The most serious adverse events reported during the trial were hypersensitivity reactions to Elaprase that could be life-threatening. They included respiratory distress, drop in blood pressure, and seizure. Other frequent, but less serious adverse events included fever, headache and joint pain.

Because of the potential for severe hypersensitivity reactions, appropriate medical support should be readily available when Elaprase is administered. Patients and their physicians are encouraged to participate in a voluntary Hunter Outcome Survey which has been established to monitor and evaluate the safety and effects of long-term treatment with Elaprase.

Elaprase is manufactured by Shire Human Genetic Therapies, Inc., in Cambridge, MA.